Sail for sailing craft



Sept. 25, 1951 H. H KERSTEN SAIL FOR SAILING CRAFT 2 Sheets-Sheet 1Filed June 13, 1949 Inventor Herbe rf H. Kersren H- H. KERSTEN SAIL FORSAILING CRAFT Sept. 25, 1951 2 Sheets-Sheet 2 Filed June 13, 1949Inventor Herbert H. kelslen Patented Sept. 25, 1951 UNITED" STATES OF vfzgssaais smronsmrN-eunnrr Herbert HsKersten, Iowa City, IowaAppI-ica'tiOnJime-IS, 1949;'SerialNo.'o8;889

" This invention relates to-novel andzusefulimprovements in sailconstructions for use on variousan'd sundrytyp'es of 'sa-iling'craftr Anobject of thisinventionistoprovide a flexi ble; airfoiltyp'e' of sailbody which; will-- alter" its contour in response to variousairr'pressures in such a way as to improvethe-sailing'characteristicsofa craftand to improve: theaerody-nam-ic qualities 1' and behavior ofthe sail as itvpasses through the air and asthe; sail together withthecraftisurged throughthe waterby meansof the air pressureoccasioned-bythewind currents-incident to the sail body.

- Conventional sails; consisting-of-a singlesheet of: canvaswhichbecomes:arcamberedvsurface in response to wind pressuresare-aerodynamically ineiiicient. This inventiomprovides-a sailebodywhich will assumethecontour otanairfoii in action. It willthen-have muchhighen aerodynamic efliciency asregardseitszeffective'thrust to dragratio. Itis so designed thats'iu willra utoma-tically assume the, propercontour in response to incident'winds i Y r a The feature oi theinvention resides inthe-com struction which includes a curved: leading:--edge member, or -mast, having an, opem-bac'kand' at leastone verticalguide but: pretera-bly two disposed within the leading edgememberiandeshoes mounted for slidable amovement disposedon the guide orguides with; tubesecarriedtby the shoes so that a flexiblememberma-y'pass-through-reaoh tube and be directed: rearwardly, theflexible member having attached at its ends a long batten which may beof one or two piece. construction but whichiis carried by a flexiblebody andrspecifically in long batten pockets formed by; suitablematerial securedthereto disposed between spaced sail surfaces of thebody; and'cross members connecting' the battens. r v :1Ancillary'objectslandfeatures-of novelty" will become apparent'ito-those1skiilediin the-art; in following the description not thepreferred'iform of -"the: invention, illustrated imtheraccompmyingdrawinggwherein; V 7

Figure l is anxelevationaliviewrof the sail construction; p

Figure 2 is a sectional view-taken substantially on the' line 2-2 ofFigure 1"- seem the direction of the arrows;

Figure 3 is a fragmentary perspective view of the sail construction;

Figure 4 is a fragmentary transverse sectional view in enlarged scaleshowing internal structure of the sail mechanism;

Figure 5 is an enlarged detail of construction unl ims (01, 114-103) 2 gtaken on the-line 5-5'1 of Figure: 1 and: in the di rection of thearrows: and 1 Figure 61s a seriesa-of 'schema'tic views: showing thefunctional operation of the structure The structure of the presentinvention. "has been made" with a view to commercial feasibility. Tothis end it is necessary that the structure be relatively simplified;easily fabricated and removed. Accordingly; a-vleading' edge member H!which is smoothly curved inacross section: and which'has an open back,is adaptedfor substantially vertical disposition: on: a craft. It i's somounted on the craft as to be capable of rotary motion on its verticalaxis so: as tmpermit proper alignment of'the sail structure withincident air currents. The said '"leadingedge member has a verticalpartition '12 with a plurality 0f cross members disposed therein"supporting rails or guides l4 and It;-re'sp'ectimely'. These' rai-Is org'uides have pairs of shoes l8 and 20; respectively, mounted 1 for slidable "movement/ thereon; The guides are preferably formed with side=-grooves therei'n and the-shoes have complemental tongues disposed in thegrooves so that the: shoesare capable of onI-y vertical'movement. Thereare a flared ends' M and 26 respectively; directed backwardtowa'rd thetrailing edge of the structure. flexible element ormember as a cabl'e-ZWis cii's posed each tube; At-eachend of the flexible member Z8 t'he'reis afastener 30 releasably fixed to a ring-32 provided on sail surfacesS S-and 36, respectively, of a flexible bodymember.

T-he sai'd "flexible' -body member is preferably ma deof a conventionalmateriahand is of two spaced SBJiI-Sl-IITQCBS 34 and 36', joinedtogether" at the-trailing edge bymeans' of stitching on the The 'bo'dyis outta the desired specifica ti ons' to forrn'--a substantiallyconventional sail shapedmemb'er: v

Spaced stripstll of amaterialrsimilan tothat ofjfthe .sail: surfacesJarestitched or otherwise 'secured tonthe interior aspect of .each sailsurface 3!, and 3'6}; forming"batteng pockets; forthe dispositiomof;flexible battens. 12'- and, respec,

tively. It is noted that the illustration shows the batten made of onepiece. However, it is contemplated to use either one or two piececonstruction. In the single piece construction as disclosed in Figure 2,the two halves of the batten generally are considered individualbattens.

The leading edge portions of the body are In operation various windpressures applied" to the sides of the sail construction force'the sailconstruction to assume the position as shown at 50 in Figure 6, or at 52in Figure 6. When there is a direct head wind, thesailstructure,-

assumes the position 56 shown in Figure 6.

At the lower edge of the body there is an elastic strip 58 fastened,having eyelets 60 therein so that the string or rope 62 may passtherethrough so that it also may be wrapped around the boom or pole 64.This boom is attached to the leading edge member or mast in theconventional disposition. The elastic strip 58 permits a certain degreeof vertical resiliency in said surface 34 and 36 permitting them tomaintain an aerodynamically smooth contour in all positions relative toincident air currents.

The sail construction will, in operation, be made to function as anairfoil by properly adjusting its angle of incidence to wind currents.

It will thus provide a higher degree of impelling thrust to the forwardmotion of the sailing craft in proportion to its drag than would aconventional single surface, cambered sail. This behavior characteristicwill materially increase the efliciency of the sailing craft when it issailing close-hauled or on a broad reach.

The general construction will permit removal of the sail constructionfrom the sailing craft when not in use. Having described the claimed asnew is:

1. A sail construction comprising a leading edge member adapted forsubstantially vertical disposition on a boat, a flexible double surfacedsail body, means operatively connected with said body for restrainingthe body from flexure beinvention, what is yond'a predetermined positionin response to air pressure, meansadjustably supported by said leadingedge member for retaining said restraining means including rails, shoesslidably disposed on said rails, tubes carried by said shoes, and saidbody restraining means having a part thereof'carried by and slidablydisposed insaid tubes.

2. A sail construction comprising a leading edge member adapted forsubstantially vertical 4 therein and secured to said shoes for slidablysupporting said elements.

3. The combination of claim 2, and a boom operatively connected at anangle with said leading edge member, and resilient means secured to saidflexible body connecting said sail body with said boom.-

4. In a sail construction, a substantially airfoil shaped flexible bodymovable in response to various directional air pressures to assumevarious corresponding positions and a leading edge member having onepair of edges of the body disposed therein, pairs of battens carried bysaid ,body and means connecting opposite battens of each pair, flexibleelements secured to the ends of the battens of each pair, and meanscarried by saidgleading edge member securing said element to saidleading edge member including a plurality of shoes and vertical guideshaving said shoes disposed thereon.

5. A sail construction comprising a curved leading edge member having anopen back and at least one vertical guide disposed within said leadingedge member, shoes disposed on said uide and tubes carried by saidshoes, a sail body formed of two thickness of flexible ma-/ terialjoined at the trailing edges thereof form'- ing two sail surfaces,longitudinal members carried by said material and forming pockets, andmeans disposed in said pockets and said tubes for transmittingmovementof one of the thicknesses to movement of the other thickness ofmaterial.

6. A sail construction comprising a curved leading edge member having anopen back and at least one vertical guide disposed within said leadingedge member, shoes disposed on said guide and tubes carried by saidshoes, a sail body formed of two sheets of flexible material joined atthe trailing edges thereof, members carried by the inside surfaces ofsaid sheets forming pockets, and means disposed in said pockets and saidtube for transmitting movement of one of the sheets to movement of theother sheet of material and including pairs of battens, the battens ineach pair being connected together at the leading edge by flexibleelements disposed in said tubes.

7. The combination of claim '6, and a plurality of cross membersdisposed between said sheets and secured to said pairs of battens.

' HERBERT H. KERSTEN.

REFERENCES CITED The following references are of record in the file ofthis patent: V V

. UNITED STATES PATENTS 7

